Stem and mount construction



Aug. 17, 1943. c. 1.. FANTUR' STEM AND MOUNT CONSTRUCTION Filed Aug. 10, 1942 i M am; ll

Inventor: Charles L. Fantur,

WM His At'torneg.

Patented Aug. 17, 1943 STEM AND MOUNT CONSTRUCTION Charles L. Fantur, East Cleveland, Ohio, assignor to General Electric Company, a corporation of New York Application August 10, 1942, Serial No. 454,339

3 Claims.

This invention relates to filament mounts suitable for incandescent lamps or other electrical devices, and especially for lamps in which a relatively concentrated light source is desirable, and a relatively high wattage at low voltage, as in the case of certain lamps for producing a definite light beam, such as automobile spotlight lamps, for example. One important aim of the invention is to obviate or minimize deterioration or failure of the inlead seal of such a lamp, owing to the heat to which the seal is subjected because of the high temperature of the concentrated filament and the high amperage current carried by the leads. Other features and advantages of the invention will become apparent from the description of a species or form of embodiment of the invention, and from the drawing.

The drawing is a tilted or perspective view of a lamp conveniently embodying the invention, a portion of the outer lamp envelope being broken away.

The drawing illustrates an incandescent lamp with an ordinary type of bulb or envelope It that includes an inward extending hollow stem H with a seal I2 at its inner end. The lamp may be mounted in an ordinary base l3, here shown as of bayonet type. Besides the stem H, the lamp mount may include the usual exhaust tube It, inside the stem, fused and opening laterally through the stem wall in or just below the seal l2, and itself sealed or tipped off at l5. The current leads I6, 87 that connect to the shell and center contacts |8, |9 of the base I3 are sealed through the stem seal l2 and extend therefrom inward into the interior of the bulb ID to supply energy to the incandescent filament 20, which may be a coil of refractory metal, such as tungsten, and is shown bent into a hairpin shape. The lamp bulb It may have the usual gas filling (such as 88 per cent argon and 12 per cent nitrogen), at an absolute pressure of 600 mm. of mercury at ordinary atmospheric temperature.

As here shown, each of the inleads I6, H is composite, consisting of multiple wire strands 2|, 2| extending separately through the stem seal l2, and spaced "well apart therein. Thus atthe seal l2 the individual wires 2| lie at the corners of a rectangle which is very nearly a square. Outside the seal |2, the wires 2|, 2| of each lead l6, ll may be twisted together as shown, to facilitate handling them and connecting them to the base contacts i8, i9. Inside the seal H, the two wires 2|, 2| of the set forming each lead l5, l6 are slightly offset toward one another in their common plane at 22, 22, and are also both bent (below their oflsets) to slope and diverge outward away from the other lead. At their upper ends, the wires 2|, 2| of each lead It or ll are con- Elected or attached to a stout spud 25, which as here shown consists of a, single stout wire laterally welded to the wires 2|, 2|, instead of being formed by twisting the wires 2 l, 2| together. As shown, each spud 25 lies between its Wires 2|, 2|, and these wires are welded to opposite sides of the spud directly opposite one another, making a strong, rigid structure not easily bent or twisted out of shape. The coiled filament 20 has its ends laterally welded to the adjacent ends of the spuds 25, 25, as shown, at the same sides thereof. The spuds 25, 25 extend laterally from the leads l6, l1 and are preferably in axial alignment with one another. With the spuds 25, 25 extending inward toward one another as shown, their inner ends lie close together; but the hairpin arrangement of the filament 20 nevertheless allows it to be made of ample length.

Besides the structural advantages already referred to, the construction described offers important advantages in increased average lamp life, because of the better performance at the seal I2. With the usual two-wire construction, lamps in which relatively high wattage is developed in a very compact filament arrangement and in a small bulb show many failures due to cracking or other airing up at the seal l2. This is especially true for certain lamps of low voltage and high current, such as a 100 C. P. 5.5. v. lamp in a G16% bulb operating on a current of 12 amperes. As well understood commercially, a G16 bulb is a spherical or globular bulb 2 inches in diameter, a small space and wall surface for so much energy as 66 watts. With the multiple wire lead construction, both the heat conducted along the leads l5, I! from the filament and that developed in the leads themselves is more evenly distributed in the seal l2, and fewer seal cracks or other early lamp failures occur. Moreover, the large surface of the large spuds 25, 25 and the spread of the four wires 2| inside the bulb l0 allows freer dissipation of' heat by radiation from the leads before it reaches the seal. Being each smaller than a singlewire' of current-carrying capacity equivalent to two of them, the wires 2| are easy to bend after sealing in,so that fewer seals are broken or cracked in bending the wires for the purpose of completing the mount. For a 100 C. P, projector lamp such as above referred to, the inleads 2| may be of 30 mil nickel and the spuds 25 of mil nickel. This gives much better results than the ordinary constructlon with but two inleads of 50 mil nickel,

or larger.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A stem and filament mount construction comprising a stem with sealed end, pairs of multiple leads sealed through the sealed stem end and extending therefrom, spuds attached to the leads of respective pairs and extending therefrom toward one another, and a coiled filament connected between said spuds.

2. A stem and filament mount construction comprising a stem with sealed end, pairs of multiple leads sealed through the sealed stem 15 attached to the leads of respective pairs and extending therefrom, and a coiled filament connected between said spuds.

CHARLES L. FAN'I'UR. 

